Illuminated panel



Nov. 9, 1954 E. A. NEUGAss 2,693,655

ILLUMINATED PANEL Filed July 3, 1951 INVENToR. fDW/N A. NE'UG/S A T'NEY United States Patent O ILLUMINATED PANEL Edwin A. Neugass, White Plains, N. Y. Application July 3, 1951, Serial No. 235,043 12 Claims. (Cl. 40-130) The present invention relates to improvements in panels, such as those used for mounting aircraft instruments, and is particularly directed to panels of the described character Which are internally illuminated.

Internally illuminated panels have heretofore been proposed, as in U. S. Patent No. 2,518,726, issued August l5, 1950, in which a core or body of a transparent, light transmitting material or medium is laminated between sheets of translucent light colored material and layers of dark colored opaque material are formed on the surfaces of the translucent sheets, with the opaque layer facing the viewer being penetrated to expose areas of the underlying translucent sheet defining the desired characters or indicia. In such panels, the light-transmitting core or body is internally illuminated and transmits the light to its portions remote from the light source by reflection of certain of the light rays back into the body at the opposite surfaces of the latter covered by the light colored translucent layers, while certain other light rays directed at the surfaces of the core or body pass into the adjacent translucent sheets and are transmitted by the latter to the surface of the panel in the penetrated areas of the opaque outer layer, or facing, to illuminate the indicia or characters defined by the openings in the atter.

An object of the present invention is to provide translucent layers or sheets in panels of the described character which transmit the non-reected light to the surface of the panel at the penetrated areas of the opaque outer facing or layer with as little loss as possible.

Another object is to provide an panel of the described character which is constructed so that the portions of the translucent sheets remote from the source of light transmit a greater proportion of the light rays impinging thereagainst than do the portions of such sheets closer to the source of light so that the illumination of the indicia or characters defined by openings in the opaque outer layer or facing is uniform without regard to the distances such indicia or characters are located from the source of light.

A further object is to provide a panel of the described character wherein the eiciency of the internal light transmission is improved.

Various further and more specic objects, features and advantages of the present invention will clearly appear from the detailed description given below taken in connection with the accompanying drawings which form a part of this specification and illustrate, merely by way of example, several embodiments of the invention.

The invention consists in such novel features, arrangements and combinations of parts as may be shown and described in connection with the articles herein disclosed. by wav of example only, and as illustrations of preferred embodiments.

ln the drawings:

Fig. 1 is a front elevational view, partly broken away and in section, of one embodiment of the present invention;

Fig. 2 is a cross-sectional view taken along the line 2--2 of Fig. 1;

Fig. 3 is a cross-sectional view similar to Fig. 2, but of a panel constructed according to another embodiment of the invention and having a light source installed therein; and

Fig. 4 is a cross-sectional view, on a greatly enlarged scale, taken along the line 4 4 of Fig. 3.

In panels of the kind shown in U. S. Patent No. 2,518,726, light is transmitted through the central core or of the light rays emitted from the light source back into the core at the opposite surfaces of the latter which are covered by the translucent layers or sheets, while certain other light rays passing through the core are not reflected, but instead are passed through the translucent layers to emerge from the panels at the penetrated areas of the outer opaque surfacing or layer. Whether light rays will be mostly reflected back into the interior of the panel or will mostly pass into the translucent sheet for emergence at the penetrated areas of the opaque outer layer has been found to depend upon the angles at which the rays of light impinge against the surface of the translucent sheet facing the core. Thus, light rays which impinge against the inner surface of the translucent sheet at an angle from the normal greater than a critical angle are reflected back into the body or core medium, while those rays impinging at angles to the normal less than the critical angle are absorbed in the translucent sheet and transmitted by the latter to the surface of the panel.

According to the present invention uniformity of the intensity of light transmitted by the translucent sheet to the front surface of the panel at the penetrated areas of the opaque facing is achieved by curving the front of the panel so that the portions of the front translucent layer remote from the light source incline toward the latter to permit a greater portion of the light rays impinging against such remote portions to impinge thereagainst at angles less than the critical angle. Thus, the tendency of the light rays, emitted from a source within the panel, to impinge against a flat front translucent layer at angles, relative to the normal, which increase progressively with the distance from the source is counteracted so that similar proportions of the light rays are transmitted by the front translucent layer at all distances from the light source.

In Figs. l and 2, a laminated panel 10 is illustrated embodying this feature of the present invention. The panel 10 includes a core or body 11, which provides the structural strength and is, therefore, preferably made thicker than the other laminae or layers. The core or body 11 is light-transmitting and preferably formed of a plastic material, such as, for example, one of the class of acrylic resins and their polymers and copolymers, methyl methacrylate having been found most suitable, although other light transmitting materials, such as, quartz, may be employed. The core or body 11 is formed with a convex front surface 12 (Fig. 2) and is surrounded by a light colored translucent sheet or layer body by reflection of certain 13, of appreciable thickness, which is preferably formed.

of a plastic composition more fully described hereinafter. The panel 10 is completed by an outer layer or facing 14 of dark colored, preferably black, material, a plastic of the class of polyvinyl or vinyl resins or materials, their polymers or copolymers being preferred.

The lamination of the core 11, sheet 13 and outer layer 14 may be performed by coating the several confronting surfaces thereof with a suitable adhesive and then pressing the sandwich together to squeeze out the excess adhesive and assist in forming the bond. Another method of performing the lamination is to place the core 11 in a press with heated platens between sheets of the translucent plastic material and bond them together by means of heat and pressure. placed in the press between layers of opaque plastic material and a new lamination made by application of heat and pressure.

After the lamination has been formed as above, a bore or opening 15 is formed therethrough to accommodate a panel light of conventional form, such as, panel lights manufactured under part #A4291 by Grimes Mfg. Co., Urbana, Ohio, and the opaque outer layer 14 is engraved away at suitable locations on the curved front of the panel, as at 16, to thereby expose the underlying portions o'f the translucent sheet 13 for defining the desired indicia or characters.

Referring to Fig. 2, it will be seen that light rays, such.

as the rays A1 and A2, emitted from a source A in the bore 1S impinge against the curved surface of the translucent sheet 13 facing the light transmitting core at substantial angles to such surface, by reason of the con- This lamination is then v 7. A panel as set forth in claim 5, wherein said front wall is outwardly convex, and said light admitting means is disposed at the location in which said front and rear walls are spaced apart the maximum so that the portions of said translucent layer carried by said front wall and remote from said light admitting means are disposed to transmit light outwardly to the front surface of the panel with substantially the same intensity as the portions of the translucent layer adjacent to said light admitting means.

8. A panel comprising front and back layers formed of a clear light transmitting material having widely dispersed pigment particles suspended therein, said front and back layers enclosing a light-transmitting medium therebetween, and outer layers of opaque material superimposed on said front and back layers, the outer layer of opaque material covering said front layer having an opening therethrough covered at its inner end by said front layer, said panel having means for admitting light to the light-transmitting medium between said front and back layers to transilluminate the front layer at said opening in the covering opaque layer.

9. A panel as set forth n claim 8, wherein said lighttransmitting medium is formed by a core of solid transparent material laminated between said front and rear ayers.

10. A panel as set forth in claim 8, wherein said front layer and the opaque layer superimposed thereon are outwardly convex and said light admitting means is disposed at the thickest portion of the panel with the convexity being symmetrical thereabout so that the parts of said front layer remote from said light admitting means are inclined toward the latter to equalize the transillumination through said front layer, said back layer being at and said light admitting means being disposed at a distance from said front layer substantially less than the radius of curvature of the latter.

11. A panel as set forth in claim 8, wherein said outer layers of opaque material are provided by a hollow box structure, said front and back layers being carried by the internal wall surfaces of said box structure, and wherein said light transmitting medium consists of air contained in the hollow interior of said box structure.

12. A panel as set forth in claim 11, wherein, the wall of said hollow box structure carrying said front layer is curved to substantially equalize the transillumination of said front layer.

References Cited in the le of this patent UNITED STATES PATENTS 

